Mounting structure for paper machine drainage foils

ABSTRACT

THIS INVENTION RELATES TO MEANS FOR AFFIXING HYDROFOIL BLADES TO PAPERMAKING MACHINES. IN ONE EMBODIMENT OF THIS INVENTION, THERE IS PROVIDED AN ELONGATED MOUNTING BAR WITH CHANNELS IN THE FRONT-FACING AND IN THE REARFACING SURFACES OF THE BAR TO WHICH A HYDROFOIL BLADE MAY BE AFFIXED, BY SLIDING INTO PLACE; THE BLADE HAVING A BASE PORTION IN WHICH THERE IS AN ELONGATED SLOG FORMING PROJECTIONS TO FIT INTO THE BAR CHANNELS WITHOUT SUBSTANTIL VERTICAL PLAY, AND A ROUTED-OUT CENTER PORTION OF SUCH DIMENSIONS THAT THE CRITICAL REGIONS OF CLOSE CONTACT BETWEEN THE BAR AND THE BLADE ARE SUBSTANTIALLY LIMITED TO THE UPPER AND LOWER SURFACES OF THE SLOTS AND THE CORRESPONDING UPPER AND LOWER SURFACES OF THE PROJECTIONS.

July 1973 R. WALSER ET AL 7 3,743,574

MOUNTING STRUCTURE FOR PAPER MACHINE DRAINAGE FOILS Filed July 26. 1971 omacn I ON OFTRAVEL) jly/l H 1 x N INVENTORS RUDOLPH .WALSER WILLIAM R.GlvlN AT'I'ORNE United States Patent O Int. Cl. D21f l/48 U.S. Cl. 162-352 Claims ABSTRACT OF THE DISCLOSURE This invention relates to means for affixing hydrofoil blades to papermaking machines. In one embodiment of this invention, there is provided an elongated mouting bar with channels in the front-facing and in the rearfacing surfaces of the bar to which a hydrofoil blade may be aflixed, by sliding into place; the blade having a base portion in which there is an elongated slot forming projections to fit into the bar channels without substantial vertical play, and a routed-out center portion of such dimensions that the critical regions of close contact between the bar and the blade are substantially limited to the upper and lower surfaces of the slots and the corresponding upper and lower surfaces of the projections.

BACKGROUND OF THE INVENTION The uses of hydrofoil blades in papermaking machines and the various forms which such blades may take are well known in the art. In this connection, reference is made to the following: Reynolds U .8. Pat. No. 3,535,201; Goddard et al. U.S. Pat. No. 3,201,308; Truxa U.S. Pats. No. 3,140,225, No. 3,520,775, and No. 3,535,204; Jordansson U.S. Pat. No. 3,165,440; Burkhard et a1. U.S. Pat. No. 2,928,466; Rocker U.S. Pat No. 3,377,236; Knowles U.S. Pat. No. 3,239,410; Dunlap U.S. Pats. No. 3,017,930 and No. 3,027,940; Wrist U.S. Pat. No. 2,928,465; Clark U.S. Pat. No. 3,497,420. Since users of paper machine hydrofoil blades desire to change the water removal characteristics of the papermaking machine from time to time, often while the machine is still in operation, various means have been proposed for doing this. In this connection, reference is made to the following U.S. patents: White et al. No. 3,337,394; Jordansson No. 3,165,440; Roecker No. 3,377,236; Dunlap Nos. 3,017,930 and 3,027,940; Wrist No. 2,928,465; Truxa No. 3,140,225, No. 3,520,775, and No. 3,535,204; Goddard et al. No. 3,201,308; Reynolds No. 3,535,201. It is also desired to effect such water removal changes by completely removing blades while the machine is in operation and various means have been proposed for achieving this as well. In this connection, reference is made to Truxa U.S. Pat. No. 3,535,204, Jordansson U.S. Pat. No. 3,165,440, and White et al. U.S. Pat. No. 3,337,394. However, until the advent of the present invention, none of these proposed solutions have proved entirely satisfactory to traversing the apparent dilemma between, on the one hand, providing a mechanically simple, inexpensive means for easily removing and/or installing hydrofoil blades in the contaminant-ridden environment of the forming section of a papermaking machine while, on the other hand, ensuring against vertical motion of portions of the hydrofoil blade under the dynamic conditions of use which cause angular variations between the upper surface of the blades and the underside of the associated forming medium with consequent adverse variations in the rates of water extraction from the furnish and in other paper formation phenomena. (In this connection, see White et al. U.S. Pat. No. 3,337,394.) That the previous solutions have proved unsatisfactory is evidenced by Woodward Canadian Fat.

No. 850,365 which contemplates a machine to force allegedly slidable hydrofoil blades into position on T- shaped base mounts because men unaided by machines have been found ineffectual to do so, particularly on wider papermaking machines.

Thus, it is an object of this invention to provide a means for slidably affixing hydrofoil blades on papermaking machines.

It is another object of this invention to provide a hydrofoil blade mounting means which is mechanically simple and so is suitable for use in the contaminantridden environment of the forming section of a papermaking machine, and yet is comparatively inexpensive to produce.

Yet another object of this invention is to provide a hydrofoil blade mounting means which is compatible with existing mounting structures and, at most, requires a minimum of adaption thereof.

SUMMARY The foregoing objectives, as well as others which will be apparent to those skilled in the art, may be achieved through practice of the present invention which provides means for slidably aflixing hydrofoil blades to support means on papermaking machines, which support means include receptacles on the front and rear-facing surfaces of said support means into which corresponding portions of the base regions of said blades may be slid, being characterized by the juxtaposed top and bottom surfaces of said portions of the blades and the corresponding top and bottom surfaces of said receptacles being substantially the only critical regions of close contact between the support means and the hydrofoil blade.

DESCRIPTION OF THE DRAWINGS This invention may be better understood by a description of the embodiments of the invention which follows, and from the attached drawings in which FIG. 1 is a cross-section view of one embodiment of the present invention,

FIG. 2 is a cross-section view of another embodiment of the present invention, and

FIG. 3 illustrates optional base mounts which may be utilized in the practice of the present invention.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION Referring first to FIG. 1, there is depicted a hydrofoil blade 10 shown slidably aflixed to a corresponding blade mount 20. As is well known in the hydrofoil art, the hydrofoil blade 10 has a leading surface 12 positioned at an acute angle with respect to a top surface 114 by which the associated forming medium 15 is supported. The blade 10 also has a trailing surface 16 which diverges from the underside of the forming medium at a very shallow angle, typically in the range of U S", by virtue of which a region of negative pressure 17 between the trailing surface and the underside of the forming medium is dynamically generated by the motion of the forming medium past the hydrofoil blade. In this connection, it should be noted that as used herein for purposes of orientation, leading and front-facing mean the direction from which the associated forming medium moves when the paper-making machine is in normal use; trailing and rear-facing mean the direction toward which the associated forming medium moves; top means the portion facing the associated forming medium; and bottom and base mean the portion facing away from the associated forming medium.

The blade mount 20, which is generally oriented with its long axis transverse, or in the cross-machine direction, at right angles to the direction of travel of the forming medium, in the paper-making machine, includes a frontfacing receptable 19 and a rear-facing receptacle 21, into which are positioned respectively projections 31 and 33 formed by portions of the base portion of the hydrofoil blade 10. Preferably, this support means may be made from stainless steel although any other material having suitable chemical and mechanical characteristics for the application may be used according to known per se principles of materials selection. In the operation of the present invention, the only dimensional relationships in the mounting portions that are critical are the thickness of the projection 31 with respect to the height of the receptacle 19 and the thickness of the projection 33 with respect to the height of the receptacle 21; substantially all of the remaining surfaces of the slot in the base of the hydrofoil blade merely being so dimensioned and positioned that they do not come into intimate contact with the corresponding surfaces of the support bar 20, except, optionally, for intermittent support strips which, for example, might be positioned between the top 36 of the base and the bottom 34 of the base slot 38 in the blade 10' to aid in preventing a blade 10 made from plastic from dishing or deflecting downward to form a depression in the middle region. By this means, it is comparatively easy to slide the hydrofoil blade on and off the support bar, yet at the same time, due to the close tolerance between each of the base projections and its corresponding bar receptacle, the hydrofoil blade is effectively prevented from altering the angular relationship between the underside of the forming medium and the trailing surface of the hydrofoil blade, thereby enhancing and stabilizing the dynamic water removal characteristics of the hydrofoil blade. Thus, for example, a considerable gap 3-8 may exist between the undersurface 34 of the routed-out portion of the hydrofoil blade and the corresponding upper surface 36 of the support bar. Similarly, there may be substantial gaps in the regions 40, 42, as well as in the regions 44, 46 between the ends of the blade projections and the sidewalls of the bar receptacles. In contrast, however, the tolerances between surfaces 24 and 30, 32 and 27, 22 and 26, 28 and respectively are comparatively small. By virtue of these small tolerances, vertical stability, with respect to the other parts of the papermaking machine, and more particularly, the forming medium, is imparted to the front and rear of the hydrofoil blades while at the same time, contact between other facing surfaces not essential to retaining the vertical, and therefore, the angular, stability of the effective upper surface of the hydrofoil blade is entirely or substantially elimi nated, or at least substantially reduced, thereby making it easier to affix the blade to the bar and to remove the blade from the bar by sliding. Of course, some of the remaining juxtaposed surfaces may be more or less in contact, but the less the amount of contact, the greater will be the ease in installing the blade on the bar and removing same therefrom.

EXAMPLE As shown in FIG. 2, a hydrofoil blade illustrated in FIG. 2A was made for affixation to a mounting bar shown in FIG. 2B. Certain dimensions of the various components were as follows:

The blade was affixed to the bar by sliding it onto the bar with the projections '50, 51 of the blade positioned in the receptacle '60, 61 of the bar. Once mounted, the

blade showed no rocking or vibration motion. Removal of the blade was found to be accomplished with case.

Of course, in addition to making the base mount by channeling out front and rear-facing receptacles from bar stock, it is also possible to achieve substantially comparable structural results by alternative structural means. Such alternative means includes aflixing an elongated piece which is T-shaped in cross-section atop a flat plate whereby the frontward and rearward facing receptacles will be formed. It should be understood that although the embodiments as heretofore described have included bar-like supports with front and rear-facing channels as receptacles for the corresponding portions of the associated hydrofoil blades, the present invention is by no means limited to such bar-like supports but may also be embodied in other structures having, in effect, front and rear-facing receptacles for the bar base projections such that vertical movement of the projections within the receptacles is effectively substantially eliminated while the remaining surfaces of the support are substantially out of contact with the corresponding surfaces of the associated bar.

Thus, there are shown in FIG. 3 forms of support members which may optionally be used in the practice of the present invention, and are particularly advantageous for use as replacements for other existing bar-like structures having tapped screw holes in the suport bases. Thus, embodiments 3A and 3B include screw member 70, and intermediate collars 72, with the threaded portion 74 of the screw member 70 inserted into the tapped holes 76 in the base plate 78. In the embodiment shown in FIG. 3B, the head member 80 of the support means is integral with the threaded portion 74 of the screw member 70, where as in the embodiment shown in FIG. 3A, the screw member 70 is inserted through a separate head member 82 of the support means.

Although these constituent parts 82, 72, 80, 72 may be square or rectangular in horizontal cross-section, they are advantageously made round so that they need not have any particular orientation with respect to the cross-machine direction of the papermaking machine along which the hydrofoil blades are slid into place. In whatever the exact configuration, the critical relationship again will be the height of receptacles with respect to the corresponding dimensions of the projections in the base of the associated hydrofoil blade since a series of such mounting means in tandem will, in effect, comprise, within the contemplation of this disclosure, a support means for the hydrofoil blade comparable to the channels in the base stock illustrated in FIG. 1 and FIG. 2.

While we have shown and described only particular embodiments of the present invention, it will be obvious to those skilled in the art that the illustrations given and the terms used herein are by way of illustration and not of limitation, and that aditional changes and modifications may be made without departing from the present invention in its broadest aspects. Therefore, it is the intention of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

What we claim is:

1. For use in a papermaking machine, the combination of a support means for a hydrofoil blade, said support means having front and rear-facing surfaces extending transversely of said machine, each of which surfaces includes a receptacle, and

a hydrofoil blade having an elongated internal chamber extending in the lengthwise dimension of said blade which opens to the base of said hydrofoil blade through an elongated slot which is narrower in width than said chamber whereby two opposing projections are formed between the base of said blade and said chamber, said blade being characterized by the height and width of said chamber being substantially greater than the height and width respectively of the portion of said support means above said receptacles, the distance between the closest points on opposing walls of said projections being greater than the distance between the bases of said receptacles, and the height of said projections being only slightly less than the height of said receptacles.

2. The combination described in claim 1 wherein the support means is a bar and said receptacles are grooves extending substantially the entire length of said bar.

3. The combination in claim 1 wherein said support means comprises a fiat planar base plate to which are affixed at least two members.

4. The combination described in claim 3 wherein said members are round in horizontal cross-section.

5. For use in a papermaking machine having a support means for a hydrofoil blade in which said support means has front and rear-facing surfaces extending transversely of the machine, each of which includes a receptacle,

a hydrofoil blade having an elongated internal chamber extending the length of said blade which opens to the base of said hydrofoil blade through an elongated slot which is narrower in width than said chamber whereby two opposing projections are formed between the base of said blade and said chamber, said blade being characterized by the height and width of said chamber being substantially greater than the height and width respectively of the portion of said support means above said receptacles, the distance between the closest points on opposing walls of said projections being greater than the distance between the bases of said receptacles, and the height of said projections being only slightly less than the height of said receptacles.

6. For use in a papermaking machine having a hydrofoil blade with an elongated internal chamber extending the length of said blade which opens to the base of said hydrofoil blade through an elongated slot which is narrower in width than said chamber whereby two opposing projections are formed between the base of said blade and said chamber,

6 a support means for said blade, said support means having front and rear-facing surfaces extending transversely of said machine and being characterized by each of said front and rear-facing surfaces having receptacles which are only slightly greater in height respectively than the height of the front and the rear projections at the base of said blade, by the distance between said receptacles being less than the distance between said projections, and by the height and 10 width of the portion of said support means above said receptacles being less respectively than the height and width of the portion of said chamber in said blade above said slot.

7. The device described in claim 6 wherein the support means is a bar and said receptacles are grooves extending substantially the entire length of said bar.

8. The device described in claim 6 wherein said support means comprises a flat planar base plate to which are aflixed at least two members.

9. The device described in claim 8 wherein said members are round in horizontal cross-section.

10. The device described in claim 7 wherein said support means comprises a flat planar base plate to which is afiixed a bar member, the cross-section of which is an upright T-shape.

References Cited UNITED STATES PATENTS S. LEON BASHORE, Primary Examiner R. V. FISHER, Assistant Examiner U.S. Cl. X.R. 

